Pathology of polyps detected in the bowel cancer screening programme

The success of the UK Bowel Cancer Screening Programme (BCSP) is dependent on reliable diagnosis and effective clinical management of pre-invasive adenomatous polyps. As the malignant potential of colorectal adenomas is highly variable, the purpose of histological assessment is to identify patients who will require subsequent surgery or regular colonoscopic surveillance. Our review encompasses the histopathology and differential diagnosis of screen-detected polyps, focusing on features which discriminate lesions at highest risk of malignant transformation. We explore some of the diagnostic challenges confronting screening pathology, including the characterization of serrated lesions and common mimics of dysplasia and malignancy.